1. Technical Field
The invention relates to a device for welding longitudinal seams of metal tubing with a laser welding device.
2. Description of the Prior Art
From U.S. Pat. No. 5,613,631, there is known a method for manufacturing a metal tube with a longitudinal weld seam wherein a metal band is withdrawn from a supply reel and shaped by a shaping tool into a tube with a longitudinal seam, and wherein the longitudinal seam is welded with a laser welding device. This method has the disadvantage that the laser beams reflected from the surface of the tube can dangerously and uncontrollably propagate and thereby injure people and/or damage objects.
It is known that only a small portion of the laser energy is usable as welding energy, and that a larger portion is reflected. Moreover, the laser light may not be in the visible spectral range, thus requiring more complex and expensive radiation protection.
From U.S. Pat. No. 5,658,473, there is known a method for manufacturing metal tubes with longitudinal weld seams wherein the longitudinal seam of the tube to be welded is welded with the help of two laser welding heads which are inclined in the longitudinal direction of the tube. Between the laser welding heads and above the weld seam, there is provided a water-cooled apron for absorbing the reflected laser beams and for removing the absorbed heat through the cooling water. Since the gap which has to be maintained between the laser welding heads, must be small, the apron has rather limited utility.